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Tuesday, January 20, 2015

I will be holding a second fruit tree pruning workshop in the Henderson area, in the Warm Springs and Lake Mead area, on Tuesday, January 27 from 1 to 4 PM in the afternoon. The primary focus of this workshop is on citrus and pomegranates.

Other fruit trees we will discuss include almond and fig. The workshop is free to the public but limited to 25 participants on a first-come, first served basis. Registration is through Eventbrite

Register for the event here
We will also be discussing controlling the leaf footed plant bug and correcting the yellowing of leaves on citrus. I will cover all of the management aspects for these trees here in Las Vegas

Sunday, January 18, 2015

Q. I noticed that woodpeckers attacked our Palo Verde tree.
There are probably 60 holes around the truck and main limbs. The sap is running
even though the holes are just under the surface, not deep. Any advice how to
prevent further damage and do you think this can eventually kill the tree?

A. This is probably one of the sapsuckers. Sapsuckers are
type of woodpecker and a couple different types have been documented in
southern Nevada. Some sapsuckers migrate through the valley and others maintain
a year-round presence.

Sapsucker damage to eucalyptus

They damage a variety of trees
including fruit trees and many different types of landscape trees. They
frequently come back to the same tree over and over.

The only thing you can realistically do is
exclude them from the tree. This means putting up some wire mesh, burlap or
other barrier to keep them from the trunk and larger limbs. They will still get
into limbs where it is hard to put a barrier.

I have seen the same fruit trees damaged
year after year for the past 20 years and the trees still seem to be still doing
well. Damaged trees repair themselves more quickly if they are in good health;
watered and fertilized adequately. I know it causes damage but it seems to be
not life threatening so I would let it go unless the damage gets extensive.

If this seems to be seasonal, you
could try some hot pepper sprays just before they begin damaging plants. Mark
the event on your calendar and time your applications accordingly.

Q. My friend has a lantana plant and the leaves look good
from the top to about the bottom few inches and then they turn yellow. What
might be the cause of this condition? My lantanas are getting very thin and
"leggy". Do you think I should wait until December to cut them to the
ground as some say?

A. These plants originate from wetter climates and richer
soils. As these plants get older and woodier at the base, they tend to lose
their leaves toward the bottom and keep the leaves on the more succulent stems
and new growth.

Different Lantanas for home landscaping in the desert

This is worse if the plant is not
in full sun or if it is very dense. Regular applications of fertilizer helps along
with correctly pruning the plant. Prune these plants to within an inch or two
of the soil surface in February if they are leggy. They also need plenty of
water so if water is being restricted they will also look pretty bad.

Pruned Lantana 2 to 3 inches high in February if there is cold damage or it has become leggy

Lantana loves full sun and do very
well provided the soil has been enriched and it is receiving fertilizer. If
planted in rock mulch the soil will become mineralized or lose its organic
matter content over time and the plant then does poorly.

Get lantana on a schedule every
couple of months with a decent fertilizer for flowering plants. In the spring
apply compost or composted chicken manure or something similar around the plant
and water it in thoroughly with a hose. You want to re-build some organic
matter back in that soil again.

I had several reports of grubs
feeding on the roots of these plants. When this happens, the plant begins to
decline. It might not be obvious to you unless you dug the plant up and
examined the soil.

If you believe this could be a
problem, you would apply a granular insecticide or a liquid drench around the
outside perimeter of the plant. Granular organic insecticides containing
rosemary and thyme oil work as well as conventional insecticides containing
imidicloprid.

Q. Last week I heard about a variety of apple called the
Pink Pearl, not Pink Lady. Will Pink
Pearl apple trees survive the Las Vegas growing season? Do you know where I can get a sapling?

A. I have heard of Pink Pearl apple but I don't how it will
perform here. Nearly any apple tree will grow in our climate but it’s really a
question of how good the fruit will be. It originated in Humboldt County,
Northern California, and it ripens sometime in late August or September. In Las
Vegas it might ripen a couple of weeks earlier than that.

Pink lady Apple fully ripe in mid to late November in Las Vegas

The eating quality of a specific
variety of fruit is affected by the climate where it is grown, the soils and
how it is managed. Pink Pearl has a good reputation in northern California but
its quality is unknown in our hot desert climate. I would hate to see you wait
four or five years only to find out the fruit is not good quality.

I am confident it will set fruit
for you provided it gets pollinated. In its place, I would advise you to select
an apple that ripens very early in the summer or in the fall months and avoid apples
that ripen during the hot summer months. My experience with apples that ripen
in July through August here has not been promising.

Q. I have a rosemary bush in the front yard that's very
healthy but has grown quite big in the seven years since it was planted. Is
there a technique to trimming? I tried once before and it looked like a really
bad haircut.

Rosemary with a bad haircut from overzealous hedge shears

A. Any older, woody plant will have its leafy growth on the
perimeter of its canopy. If the plant canopy is dense, which is typical of
rosemary, all of the leafy growth will be in a 2 inch layer along the outside
of its canopy.

Leafy growth needs sunlight. Shade
causes leaf drop and prevents leaves from developing. Dense plant canopies
don’t allow sunlight to the interior. This means that the woody growth in the
interior will be leafless, bare, naked. If you begin cutting away deeper than 2
inches then you will expose the interior, bare wood. This does look like a bad
haircut.

The good thing is that bad haircuts
are not permanent. New growth emerges from these bad haircut areas because of
sunlight and the stimulation the plant receives when it is pruned.

Rosemary pruned around the tree

Shaping plants should begin when
they are young. You cannot wait until they are several years old to begin
shaping them unless you are willing for that plant to have a bad haircut for a
while.

Pruning rosemary depends whether
you want it as an ornamental or you plan to harvest the rosemary for cooking.
If you are harvesting rosemary for cooking you want to harvest soft succulent
growth.

Alternatively you can harvest the
woody growth and strip the leaves off. Commercially pruning is done with a
shears because it is faster. Again, if you cut too deeply with a shears it will
look like a bad haircut.

After pruning always make sure
there is enough warm weather for regrowth to occur. Water and fertilize the
plant to stimulate new growth and recover from pruning.

If you want your rosemary to be an
ornamental, it can adhere to any shape you want to give it. It can be sheared
or it can be pruned with a hand pruners. During this last holiday season we saw
upright rosemary pruned into small Christmas trees available at nurseries and
garden centers. Just don’t cut the plant too deeply.

Rosemary pruned more formally like bangs in a haircut

I prefer a more normal look. This
is done by reaching deep inside the plant and removing older wood with a hand
shears. By reaching inside to make cuts they are hidden by the remaining growth.
If you prune like this, it will never look like the plant was pruned; just
smaller.

Rosemary pruned informally

Look for the longest growth, follow
the stem back inside the canopy to a place where it joins another branch. Cut and
remove the longer stem and leave the shorter one. This would be done in several
places each year to keep it restrained.

Q. I
have some of these roses that are the kind that they said are ground cover type
but they did very poorly in the Summer, when it was hot. Now I have planted
them in the shade and they leaves are turning white then falling off. Could it be that these expensive roses from the Cal coast will not do well
here? My other roses are looking great now and getting higher and higher.
These ground cover roses have never looked or done well.

Actually this is a very good climate for roses. The very
worst time of the year for them is Midsummer. When planting roses they need
full sun and lots of soil amendment at the time of planting. They benefit from
2 to 3 inches of wood chip mulch on the surface of the soil surrounding the
plants.

They don't have a lot of pest problems like they would in wetter parts
of the country but in the shade you might expect powdery mildew. Powdery mildew
will cause the upper surface of the leaves to turn white and fall from the
plant. Powdery mildew seldom occurs if roses are growing in full sun and if
they are irrigated through drip irrigation, not overhead irrigation. Overhead
irrigation encourages the development of powdery mildew on rose leaves and
flowers.

Welcome to Xtremehorticulture

Home. My home base is Las Vegas, Nevada, in the Eastern Mojave Desert. This blog focuses on horticulture in Deserts.

Me. Desert Horticulture is very different from horticulture in wet climates. Very few people talk about it. This blog focuses on it. My experience in horticulture span over 50 years; time as an applied academic and now working as a consultant. This blog shares my experience and advice in Desert Horticulture. Work in Northern, East and Southern Africa, Western and Central Asia and the Middle East have expanded my views on Desert Horticulture.

Questions. I reply to questions sent to me as quickly as possible. Please include pictures. It helps. Unless questions are confidential, I post them on this blog if they add new information.